Friday, November 24, 2023

Our Color-Coded Forest -- v2023

Happy Thanksgiving to readers of Princeton Nature Notes, now 17 years old--the blog, that is, and maybe even some of the readers. I will be leading a nature walk this Sunday, Nov. 26, from 1-3pm, open to all. Meet at the main parking lot for Herrontown Woods, off Snowden Lane. I had hoped to show off what I call the color-coded forest, but a storm of heavy wind and rain stripped most shrubs of their remaining leaves. It will still be good to have a hike, though, and you can see in this post what area woodlands looked like until just a few days ago.

November is when woodlands turn into one of those paintings where you match the color to the number. It's a time when you can gaze into the distance and identify every woody plant by its color. For instance, in this photo of a woodland overlooking the canal in Kingston, check out the yellow in the upper right. That's what's left of the Norway maple leaves, which turn color later than the native maples, and seem to know no other color than yellow in the fall. And the green in the understory? That is bush honeysuckle--what I call the "second forest." It's still green because it evolved on a different continent with a different climate, and so its timing is different from the native flora in spring and fall.

Seen this past week from the cliff in Herrontown Woods, the color coding was much more complex, with non-native Photinia, winged euonymus, and bush honeysuckle mixing with native species.  
Here's a glorious dogwood along the red trail. 
Up on the ridge, the maple-leaved Viburnums develop subtle shadings.
In our "cultural zone" between the Barden and Veblen House, young white oaks turned a rich burgundy earlier in the month. I tell people it's called a white oak because it turns red in the fall. Red oaks mostly turn orange. Naturalists have been doing Stop Making Sense tours long before David Byrne got around to it.
And then there's Photinia villosa, which is both beautiful and concerning, given how densely it has come to dominate in areas across town in Mountain Lakes and the Institute Woods. A few specimens turn bright orange, while
most turn bright yellow, even when growing side by side. You won't see a Norway maple going rogue with orange in the fall.

Another shrub, related to Photinia but just starting to show up in our woods, is a mystery. I discovered it across town fifteen years ago in Rogers Refuge, and even crack botanists have yet to put a name on it. 

Here you can see Photinia (yellow), American holly (evergreen), and in the foreground some sweetgum leaves (red). You can see how empowering the color coded forest is for distinguishing one species from another. 
Barberry is beautiful as well. If only wildlife could feast on beauty, we'd be all set.
Bush honeysuckle--here photographed mid-month with a background of pink winged euonymus--keeps its leaves longer than other nonnatives. Even after all that wind and rain, it could still be easily spotted, clinging to its leaves. 
A less common nonnative called jetbead (Rhodotypos scandens) has found its way into one area of Herrontown Woods near the little red barn. Like bush honeysuckle, it keeps its leaves late into the fall. Having blended in all summer, it suddenly becomes exposed this time of year, thanks to the color-coding.

Small patches of this unusual native grass, found thus far only in a couple spots along the ridge, are easily spotted now as well. 
You can see the long awn on the seed that gives this grass an attractive look, as if it has fancied itself up with long eyelashes. The coppery background leaf is beech, which will keep its leaves far into the winter, a reminder of November's color-coded artistry.

Past posts about the color-coded forest

Monday, November 13, 2023

Liz Cutler's Pressed Flower Art

This is a post to honor the work and artistry of one of Princeton's great environmental educators, Liz Cutler. I first knew Liz as founding director of the nonprofit OASIS (Organizing Action on Sustainability In Schools), which promoted sustainability at 23 area schools. As sustainability director at Princeton Day School, she organized school garden tours and climate summits focused on mobilizing and empowering the next generation. Once a year, PDS would send a hundred kids to Mountain Lakes for community workdays back when I was the resource manager there. Later, we served together on the Princeton Environmental Film Festival committee.

Since leaving PDS, Liz says she's been consulting with schools all over the country to help them become more environmentally sustainable. One particularly nice-sounding gig: she spent this past winter as Master Teacher-in-Residence at The Island School in The Bahamas helping their young faculty improve their teaching practice.

To her extraordinary environmental work has more recently been added extraordinary art, specifically pressed flower compositions. According to Liz, what "began as a meditation in 2020 has become a creative manifestation of my love of nature and of my life's work as an environmental educator." 

Less than two years after she started creating her many and varied compositions of pressed flowers, the Princeton Public Library hosted an exhibit of her work

She now has a website, LizCutlerPressedFlowers, where she makes prints of her original compositions available for purchase as lasting gifts. The website is an opportunity to check out all her lovely work, and includes a description of her process. Twenty percent of all proceeds go to benefit The Watershed Institute and the D&R Greenway Land Trust. 

Saturday, November 11, 2023

The Pleasure and Aesthetics of Native Seed Collection

One of the more pleasurable and aesthetic outdoor experiences in the fall is gathering seeds. I claim no expertise, but adhere to one simple rule: let the stem below the seeds turn brown before harvesting. And harvest when the seeds are dry. Also, be messy. Let some of the seeds fall where they would have fallen if you hadn't come along to take some. Alright, that's three rules. But that last rule is especially enjoyable. How many times in your life have you been told to be messy? 

There are more official rules out there for seed collection, particularly of uncommon species, but nearly all the seeds I collect now are either from my backyard or the Botanical Art Garden, both of which I planted. It's gratifying to see these new populations of local genotypes thriving, and to expand their local presence further. 

The plants I harvest from tend to be generous towards a human tendency to procrastinate. Many species hold on to their seeds for months in the fall and into the winter. But the prettiest time to be picking them is sooner rather than later, as they become increasingly weathered and threadbare as winter progresses.

Harvest of wild senna, seen in the first photo at a lovely stage when the leaves contrast with the dark seed pods, can be postponed considerably, as the pods hold onto the seeds for months.

The bright, fluffy clusters of ironweed seeds are easy to identify on stems that can reach 8 feet.

Rose mallow hibiscus (Hibiscus moscheutos) holds its seeds in convenient cups. Best not to wait too long, because there's a slow attrition to spillage and insects as winter sets in.

As with other sedges, the seed clusters of morning star sedge (Carex grayi) will break apart as fall progresses. Some other local sedges with easily collectible seeds are squarrose sedge and fringed sedge.
The seeds of bottlebrush grass, attractively arranged along the stem, were already starting to fall off when I collected them in late October. Just grab the dried stem between thumb and finger and pull upward to strip the seeds. This is an attractive understory grass. 

The seeds of turtlehead (lower left in the photo) are still ripening, having shown their own form of procrastination, waiting until early fall to bloom.  

Collecting seed has extra meaning and purpose this fall, because many of them will be planted along a wooded slope in Herrontown Woods where a large clone of wisteria had pulled down some of the trees, creating openings where sun can reach the ground. Years of effort, particularly with the consistent, transformative work over the past year or two by volunteer Bill Jemas, has largely snuffed out the daunting wisteria clone that had taken over an acre or two, choking other growth as it steadily expanded along this broad hillside. It even somehow traversed the creek and was headed towards the Botanical Art Garden, adding another layer of urgency to knocking it out. Into the void created by our wisteria removal has come garlic mustard and stiltgrass, but this year we pulled those before they went to seed. 

With much of the slope now bare (the photo shows wisteria to the right, cleared areas to the left), it's time to introduce native plants. We could toss the seeds hither and yon, but I like to give them a better chance by being more deliberate. Deer are an issue, of course, given their appetite for native plants, and my plan is to plant seeds in small circles here and there, creating loci a couple feet wide. I like to scrape a thin layer of dirt away, scatter some seeds, then sprinkle some dirt on top and tamp it down. Then I'll place a 3 foot high plant cage around each circle. Those that grow inside the cage should be protected enough to mature and produce seed that can then scatter beyond the cage on its own in subsequent years. 

It's actually a good way to find out which species the deer leave alone, and which they munch on. We are, in a way, creating "deer feeders" by protecting a few plants inside the cages--plants that each year spread beyond the cages, where the deer can eat them. This approach has been successful at the Barden. Thanks to the town's investment in annual deer culling, many of the plants that sprout beyond the cage survive. 

Of course, all of this thus far is talk. Procrastination is a particularly powerful factor when it comes to getting plants or seeds in the ground. There's so much other work to be done! What's real and lovely, and has actually happened, is the seed collecting. 

Wednesday, November 01, 2023

The Fiery Look of Prairie Grasses in Fall

These little bluestem grasses (Schizachyrium scoparium), planted in front of town hall in Princeton, looked like they were on fire last week when backlit by morning sun. The last time I saw prairie grasses turn a fiery color in the fall was thirty years ago, when I lived in Ann Arbor, MI. Indian grass and big bluestem would turn bright yellow and orange at the base, making them look as if they were aflame. 

The mimicry of fire was fitting, because prairie grasses are adapted to thrive where periodic fires sweep through. Each fall, when they die back to the ground, they leave above them persistent remains ready to feed a fire. If no fire comes, that persistent dead foliage can get in the way the next spring, casting inhibiting shade on the new growth. 

No fire will sweep through this ornamental planting. Hopefully, someone will imitate fire to some extent by cutting the old stems to the ground next spring so the new stems can grow unhindered.

Little bluestem is shorter and more persistently erect than other prairie grasses like big bluestem and Indian grass, and so fits better into an ornamental planting. Here it is in the courtyard at Maplewood, a nearby retirement facility where our Onstage Seniors documentary theater group recently performed.

And here it is growing near the Princeton University soccer stadium along Fitzrandolph Road, mixed with switchgrass and other native grasses. 

The fiery version in front of town hall was surely a cultivated variety bred for especially dramatic color. But the prairie grasses in Ann Arbor that appeared to be aflame were wild. For some reason, perhaps a milder climate, the same species growing wild at Tusculum or along the gas pipeline right of way in Princeton don't attain that dramatic fall look. 

When I lived in Durham, NC, I often found additional species of native prairie grass persisting beneath powerlines, where they were spared the stifling shade of trees. One that was particularly beautiful when backlit was splitbeard bluestem. Its cottony-like seeds seemed to glow when they caught the autumn sunlight. 

It's good to see native prairie grasses showing up in plantings around town. The university seems to be learning how to maintain them better, which means catching the weeds early. Nice to be surprised by some sideoats grama poking through the fence at the soccer field.


Friday, October 27, 2023

Update on Native Butternuts and Chestnuts in Princeton

There's a lot of gratitude being expressed towards trees these days. The gratitude tends to be towards trees in general, but this fall, I'm especially grateful for three trees in particular. 

All three, growing at the TRI property, are among many that have been planted over the years by local nut tree expert Bill Sachs and me as part of an effort to bring back two marginalized native tree species. One is an American chestnut. The other two are butternuts. Both of these species have been laid low by introduced diseases, and I feel fortunate to be part of an effort to make them numerous once again in Princeton. 

The two butternuts at TRI bore a bumper crop this year, some 200 nuts--the first sizable harvest since the parents to these two trees were lost 14 years ago. One fell in a storm; the other ironically was cut down as part of an environmental remediation. It's Bill who played the role of Noah, growing new seedlings from the seeds we collected from the two trees before they were lost.

We planted other members of this new generation of locally sourced native butternut trees at Harrison Street Park, Herrontown Woods, Mountain Lakes, and Stone Hill Church. Bill in particular did a lot of the followup work, checking the cages that protected them from the deer, and serving as a one man bucket brigade to sustain the trees through droughts in their first couple years.

Bill also did a great deal of work to re-establish native chestnut trees in Princeton. That project began in 2010, when chestnut researcher Sandra Anagnostakis, of the Connecticut Agricultural Experiment Station came to town to give a talk. She brought along 20 chestnut seedlings for us to plant in local parks. The seedlings were 15/16th native, 1/16th Japanese chestnut. Of all of those that Bill planted, at the Princeton Battlefield, TRI, Herrontown Woods, and Harrison Street Park, only the one tree at TRI has borne fruit. Many of the hybrid trees have died, despite the effort to breed in resistance. 

There have been some other efforts to get the American chestnut growing again in Princeton, by the Friends of Princeton Open Space at Mountain Lakes and also by arborist Bob Wells at Greenway Meadows. The best bet for repopulating our world with the American chestnut may well lie in research that led to inserting a gene from wheat into the American chestnut genome that confers resistance. This seems a much more dependable and faster way to embed resistance to the fungus, and bring back this spectacularly useful native tree. 

In the meantime, we can celebrate the hard-won harvest we're getting from this new generation of native nut trees, and after letting them cure a bit will even get to find out what a butternut tastes like.

Related posts

From 2021: Butternut Redux--A New Generation Bears its First Crop

Sunday, October 15, 2023

Lorenz Hiltner--Plant Scientist and Potential Relative

A few years ago, my brother, Bill Hiltner, got interested in running a farm-scale composting operation near where we grew up in Wisconsin. Having degrees in physics and chemistry, he's the kind of guy who would be drawn to wondering what actually goes on inside a compost pile. Before long, he came across the research that another Hiltner had been doing a century prior. 

Lorenz Hiltner, according to an article published in the professional journal Plant and Soil, was "a pioneer in rhizosphere microbial ecology and soil bacteriology research" and the first scientist to coin the term "rhizosphere," back in 1904. 

"Due to Lorenz Hiltner's research on the biological basis of soil fertility, which places soil organisms and the humic content of soils in central focus, he is recognized today as one of the founders of applied microbiology and organic farming."

One of the founders of organic farming? A Hiltner? Not that we've managed to trace any clear genealogical link, but maybe some inherited genes inclined me to start growing organic vegetables in high school, and then teach organic gardening at a summer camp called Innisfree in northern Michigan. Maybe it was some sort of genetic echo that caused me to read the 15th printing of Rodale's Encyclopedia of Organic Gardening as if it were a bible, and revel in the richness and earthy aroma of leaf mold three feet deep where the landscape crew at Yerkes Observatory had deposited big mounds of leaves each fall for decades. Or maybe it was just coming of age in the 1970s. 

Lorenz Hiltner "was born on November 30, 1862, in Neumarkt, Upper Palatinate (Oberpfalz), Bavaria, as the first son of a master in acetic acid fermentation and gastronome." A Wikipedia entry describes his father in less lofty terms, as "a vinegar maker and innkeeper." By 1885, Lorenz had completed his academic studies, and in 1896, he and a colleague patented a means of "'vaccinating' legume seeds with pure cultures of nodule bacteria," according to wikipedia. The inoculant was called "Nitragin."

Most of his research he performed in the Bavarian Agriculture-Botanical Institute in Munich, where he was the director from 1902 to 1923, building the institute from four employees up to 90. The Institute's mission was to support agricultural practices in Bavaria, but scientists came from all over the world to learn from his experience. According to wikipedia, "Until 1904, his institution was the only place in the world that supplied "vaccine bacteria" to farmers. At the 1904 World's Fair in St. Louis, Hiltner and his Agricultural Botanical Institute were awarded a gold medal." (Note: The article and wikipedia both say St. Louis, Michigan, but the Worlds Fair that year was in Missouri.)

Another quote from the article makes him sound particular relevant to today's intense interest in the give and take between tree roots and other life in the soil. While we focus on how trees and other plants support life above ground, it would seem they also give as much as they get from the soil beneath them, sending the overabundance of their photosynthetic production downward to feed soil life. 
"Hiltner became convinced that root exudates of different plants support the development of different bacterial communities. His definition of the rhizosphere in the year 1904 centered on the idea that plant nutrition is considerably influenced by the microbial composition of the rhizosphere."
Lorenz Hiltner was part of the great European tradition of cutting edge research that was the envy of American scientists early in the 20th century. In researching the lives of my "adopted ancestors", American mathematician Oswald Veblen and atomic physicist Walter Colby--both of whom traveled frequently to Europe as the century began, wishing to emulate the great institutions of learning they found there--I see a contrast in trajectories. As the U.S. rose in prominence and innovation, European scientists became increasingly hampered by political conflict and instability, even before the Nazi rise and WWII. 

Always working to advance research and apply it to people's everyday needs, Lorenz Hiltner sought to make the best of the worsening political conditions. During WWI, he "conducted intensive studies on alternative food sources for men and livestock to prevent disastrous consequences of the famine in Germany." "After the war, he managed to start his scientific journal again in 1921 despite the problems with the unstable situation and ongoing revolution and counterrevolution in Munich."

His scientific contributions were deemed worthy of a centennial symposium. From the article: 
"In the centennial symposium of Hiltner’s definition of the “Rhizosphere” in Munich in September 2004, more than 450 scientists gave tribute to his founding work on the rhizosphere and presented studies that continue on many of the ideas first brought to light by Hiltner."
He died unexpectedly, of a stroke while in his office, 100 years ago at this writing, on June 6, 1923. His work was continued by his eldest son, Erhard. Regardless of whether we discover an ancestral connection, I'm feeling some kinship. 

Sunday, September 17, 2023

Last Chance to Pull Stiltgrass

This week and maybe next are your last chance this year to pull stiltgrass (Microstegium vimineum). This mega-invasive is an annual, so the logic of countering its spread is to pull it before it can produce and drop seed. If the seeds haven't loosened yet at the end of the stalk, you can still pull it. Throw it in the trash, or if there's a lot, make a big pile of it so that any seeds that sprout the next year will all be in one place and easily covered or pulled. Definitely don't put it in your compost if its seeds are forming. If stiltgrass is just starting to invade your yard, pulling as completely as possible now will greatly limit its seedbank for next spring. Another strategy for large stands is to let the stiltgrass grow, then just as it begins to flower mow it short and hope its feeble roots don't have enough energy to grow another flowering stalk. 

For those fuzzy on identification, google lots of images, and look for the silver line running down the middle of the leaf. Stiltgrass can grow in the shade or sun, climb up to four feet, or thrive in a miniature state while ducking below your mower in the lawn. It's incredible survival skills include being incredibly inedible for wildlife. Stiltgrass gives nothing back to the habitats it increasingly dominates.

More on Stiltgrass, and a Success Story

Walking in the local woods, you've probably seen this kind of scene--what looks like a grassy meadow extending through the forest. In the filtered light of the understory, its simplicity and lushness may have some visual appeal. And yet, in some ways what you are looking at is the ecological equivalent of an urban food desert. 

Stiltgrass is an introduced plant that could be called a pervasive invasive, able to thrive most anywhere and dominate whole landscapes. Its success has come in part through being inedible. As wildlife selectively eat native vegetation, the stiltgrass expands, preventing the native plants from rebounding.

Unlike another nonnative annual weed that can look similar, crabgrass, stiltgrass becomes ubiquitous because it can thrive in sun or shade. That means the stiltgrass invading your lawn and flower beds can continue spreading ad nauseum into the nearby forest, or vice versa.

We used to call it bamboo grass--something in the shape of the leaves is reminiscent. The stiltgrass name refers to its angular growth, with each segment supporting the next as it climbs up and over fallen logs and other plants. Packing grass is another common name, referring to how it was once used to pack porcelain for shipment. That's probably how it first reached the U.S., in packing crates sent to Tennessee. 

When I first encountered it, growing on the bank of Ellerbe Creek in Durham, NC, I thought it graceful. Then came Hurricane Fran, bringing floods and fallen trees. In the aftermath of that massive disturbance, stiltgrass exploded in the landscape, expanding and ultimately choking forests with its vast, dense stands. New Jersey proved no different. 

Stiltgrass tends to establish itself along roadsides. Here it is growing in a green ribbon along Herrontown Road. Trails, too, provide an avenue for extending its reach, its tiny seeds carried on boots or the hooves of deer.

Though stiltgrass has covered large areas of woodland in the eastern U.S., we have found it worthwhile and even satisfying to counter its relentless incursions. Today in the Barden at Herrontown Woods, some volunteers pulled it out of a patch of native jewelweed along the edge of the parking lot. 

Nearby, on land where we have largely eliminated a massive clone of wisteria, stiltgrass was starting to move into the void. If nothing were done, this open woodland would have become a pasture of stiltgrass. But we have acted early enough to be able to remove all of this year's stiltgrass, dramatically reducing the seeds available for next year's crop. This photo shows the last patch before we pulled it. 

Interestingly, there are native grasses that look a little like stiltgrass, the main one being Virginia cutgrass (white grass), Leersia virginica. It has longer, narrower leaves that lack the silver stripe down the middle. As is a common ecological refrain, the native grasses "play well with others," not forming stiltgrass's massive, exclusionary stands. Some smartweeds like Lady's Thumb can also bear a resemblance. 

Saturday, September 16, 2023

Where Have All the Spotted Lanternflies Gone?

Well, it's happened, at least in our neck of the woods.

Billed as a major calamity, the spotted lanterfly invasion has gone "poof" this year. Yes, the spotted nymphs could still be found clinging to the stems of Ailanthus sprouts at our Barden in Herrontown Woods. 
And a few adults were later seen perched on the rachis of Ailanthus leaves. We pulled the sprouts out of the ground to deprive them of this haven. Hard to say where they went after that.

Writing a post about lanternflies three years ago, I learned that numbers of the invasive insect had dropped in some areas of Pennsylvania five years after first being seen. Lanternflies first showed up in Princeton in 2018, and here we are five years later, with what appears to be a dramatic drop in numbers.
It's true that people gave themselves over to squashing the pesky bugs--leafhoppers, actually--in spirited ways. (This photo shows one of the more creative approaches.) Some think the unusual weather has had an effect. Insect numbers overall have been down, be it the pollinators on backyard flowers, the odorous house ants that used to invade our kitchen, or spotted lanternflies. But my guess is that it has been the full-time predators, feathered or with eight legs or six, that are to be most congratulated for stemming the explosion of spotted lanternflies. 
Just follow the trail of colorful wings that brightened a walk up towards Veblen House one day.

The most powerful contrast for me is between the invasions of emerald ash borer and spotted lanternfly. Since the emerald ashborer arrived, about ten years ago, I have yet to see a single adult ash borer in Princeton, and yet the devastation they have brought to the ash tree is all around us. The lanterfly, on the other hand, has been seen everywhere, and yet I can't point to a single plant that has died due to their appetites. We humans are visually oriented, but it's the invisible threats--be they an invasive insect or even more significantly an overdose of carbon dioxide--that most endanger our world.

Thursday, September 14, 2023

Yew Berries and Dewberries


I've passed by this yew hedge on busy North Harrison Street thousands of times, and usually pay it no mind.  

But a couple days ago, I happened to be looking down at the sidewalk rather than the gazillion cars and trucks driving by, and saw something that caught my eye.

Yew berries! They look like small, bright red pitted olives, but the pit is definitely still there. Fifty years ago, in botany class, I learned that the juicy red part is edible, but the hard central pit is most definitely not. The side of a busy street is probably not the best place to be harvesting edibles, but I picked a few, ate the flesh and spit out the pit--an unexpected treat along a sidewalk in Princeton 

Technically, the yew berry is not a berry at all, but
an aril. All students of botany will vividly remember the moment in class when they learned that, as one website states, "in contrast to a berry, which develops from the ovary, an aril is an outgrowth of the ovule, or of the funicle which attaches it to the placenta." Botany is full of surprises.

The yew we sometimes see planted around houses is one of the few conifers native to England, according to the Kew Gardens website. America has a native yew, Taxus canadensis, which shows up on a 1960s plant inventory for Herrontown Woods, but I've never encountered it. 


One thing I discovered this year is that we have dewberries growing in the Barden at Herrontown Woods. I had thought we had three types of brambles in the Barden: blackberries, black raspberries, and the nonnative wineberries. But some of the blackberry-like plants were crawling along the ground rather than arching upwards, as brambles are more normally wont to do. These we decided were dewberries. They still have thorns, but you could say they lack spine. The whole concept of a dewberry was likable, from its less intimidating presence to the promise of fruit. They are very adventurous in some areas of the Barden, however, crawling long distances. We may need to curb their travels, even though the berries, ripening in mid-August, are pretty tasty.

Thursday, September 07, 2023

Pilewort--A Native Weed With Hidden Flowers and Showy Seeds

Some plants have it all backward. Flowers are supposed to provide the show; the seeds, not so much. 

But with pilewort, its the seeds that catch the eye, clustered in raggedy bunches that look like cotton. 

The plant sets up great expectations as it grows and grows, fleshy like a large thistle, but soft and approachable, 

with a pleasant scent when you crush the leaves. What fabulous flowers will crown all this vertical ambition? 

Something looking like a flower bud appears, but it never generates anything resembling a flower with petals. Pollinators visit nonetheless, even though the flowers look like duds. 

During our monthly nature walk at Herrontown Woods this past Sunday, I was grateful that one of the participants pointed out some other activity around the pilewort flowers. A common local ant species was busy tending to a flock of aphids sucking juice from the stems. The ants harvest the aphids' honeydew. 

Pilewort (good luck with the latin name, Erechtites hieraciifolius) is what I call a native weed. They pop up in large numbers in areas that have been disturbed, rising 8 feet high in what looks like a fleshy forest dusted with snow. 

Maybe the name comes from the piles of seeds it deposits all around. Another common name for it is fireweed, because it sprouts abundantly after a fire has swept through.

You might think this plant a menace that will take over. The nonnative lambsquarters, also an annual, can give this impression too, growing densely and tall the first year after a disturbance. But I've learned not to be concerned over their dominant presence. The first year's show of abundance fades in subsequent years until you can hardly find a one. Other plants move in, and pilewort awaits the next disturbance. 

2024 Update: Low and behold, the pilewort did not gracefully fade away this year. Having allowed it to go to seed last year, we are faced this year with a pilewort riot, requiring a sustained effort to pull it before it goes to seed again. Live and learn.